Anthony Tommasini's new biography of Virgil Thomson opens with an anecdote that paints his protagonist's vindictiveness, pettiness and personal insecurity with harrowing vividness.

In 1986, a new production of his opera, "Four Saints in Three Acts," was to be one of the main events celebrating his 90th birthday.

As a surprise, Lou Risposi, Thomson's personal secretary, had arranged for retired singer Beatrice Wayne Godfrey, one of the leads in the original 1934 production, to attend. Godfrey was 82 and confined to a wheelchair in a nursing home, but Risposi had found a way to get her there. And it was to be a high point in Godfrey's now lonely life.

Thomson got wind of the plan, however, and confronted his secretary, saying, "I do not want her there. I want you to call up and cancel these arrangements. There's nothing more dramatic than an old fat black lady in a wheelchair making an entrance!"

Godfrey was devastated, of course, but Thomson prevailed and had his moment in the spotlight to himself.

Thomson, who died in 1989 a few months before his 93rd birthday, was not a nice man. Tommasini makes this horrifyingly clear from the start. He was, however, a colorful personality who had some influence over the music of his time. He was not one of the great composers of this century, but he was an original musical thinker whose compositions carry a distinctly personal stamp.

He was openly homosexual in the days before gay rights were even a possibility, but his life was filled with secrets and lies, a self-hatred that extended to his more open gay friends and lovers. As a result, most of his relationships were unsuccessful.

Even his closest friend, lover and companion, Maurice Grosser, became involved with another man, although remaining devoted to Thomson. Tommasini explains, at one point, that Thomson "absolutely forbade Maurice to refer to the sexual component of their relationship . . . Maurice enjoyed sexual adventures, encounters with strangers. For Virgil, such encounters, though he engaged in them (more often than he admitted) were heavy with guilt and humiliation."

Thomson's years in Paris between the two world wars provide a gossipy compendium of the major arts personalities of that generation. His friendship and collaborations with Gertrude Stein influenced his music at least as much as his studies with the venerable Nadia Boulanger, who had more success with Aaron Copland, Ned Rorem and numerous other composers who attended her musical atelier.

Thomson's greatest accomplishments - and influence on 20th century music, perhaps - was as a music critic for the New York Herald Tribune from 1940-54. As a critic, he was consistently brilliant and perceptive - even fair, according to his own lights, most of the time.

A 1940 column on Mozart's "Don Giovanni" gets right to the core of this great work: "It begins with a dirty comic song, goes on to a murder, a series of seductions, a sort of detective story pursuit of the murderer in which one of the previously seduced ladies plays always a high comedy role . . . It is a moral entertainment so movingly human that the morality gets lost before the play is scarcely started."

Yet a review of a new piece by Roy Harris, a rival who achieved audience success but lacked Thomson's impressive academic (Harvard) credentials, is evenhanded: "One is tempted to put the whole thing down as insincere and a bad joke. The truth, however, is other. Mr. Harris . . . does not always get anywhere in his music, but it is serious music, much more serious than his blurbs would have us believe."

Tommasini, a critic for The New York Times, combines superb scholarship with an understanding of Thomson's unlikable persona. He does exactly what a biographer must do - bring his subject vividly to life.

By the time we get through the book's 605 pages, we have lived with Thomson, his friends and his enemies. Tommasini has made it possible to share his subject's life even as we are alternately titillated and horrified by his failings.